[bmv2] inlining + header stack broken

[smolkaj]

The following program compiles with the bmv2 backend, but throws the error

lt-simple_switch: P4Objects.cpp:710: int bm::P4Objects::init_objects(std::istream*, bm::LookupStructureFactory*, int, size_t, std::shared_ptr<bm::TransportIface>, const std::set<std::pair<std::basic_string<char>, std::basic_string<char> > >&, const bm::P4Objects::ForceArith&): Assertion `0 && "parameter not supported"' failed.

at runtime when executed on simple_switch:
158.p4.txt

#include <core.p4>
#include <v1model.p4>
typedef standard_metadata_t std_meta_t;

header h_t {
    bit<1> f;
}
struct H { h_t[1] stack; }
struct M { }

parser ParserI(packet_in pk, out H hdr, inout M meta, inout std_meta_t std_meta) {
    state start {
        transition accept;
    }
}

control VerifyChecksumI(in H hdr, inout M meta) {
    apply { }
}

control ComputeChecksumI(inout H hdr, inout M meta) {
    apply { }
}

control Aux(inout H hdr) {
    table t {
        key = {
            // the use of a stack, together with inlining, provokes the bug
            hdr.stack[0].f : exact;
        }
        actions = { NoAction; }
    }
    
    apply {
        t.apply();
    }    
}

control IngressI(inout H hdr, inout M meta, inout std_meta_t std_meta) {
    Aux() aux;
    apply {
        aux.apply(hdr);
    }
}


control EgressI(inout H hdr, inout M meta, inout std_meta_t std_meta) {
    apply { }
}

control DeparserI(packet_out b, in H hdr) {
    apply { }
}

V1Switch(ParserI(), VerifyChecksumI(), IngressI(), EgressI(), ComputeChecksumI(), DeparserI()) main;

[smolkaj]

Actually, the bug is already provoked when Aux is replaced with an empty control block:

...
control Aux(inout H hdr) {
    apply { }    
}
...

[mihaibudiu]

The last pull request under submission fixes the manifestation of this issue for this example.
However, the issue remains for a different example, if we inline the header twice, so I will leave it open until it is fixed:

control IngressI(inout H hdr, inout M meta, inout std_meta_t std_meta) {
    Aux() aux;
    apply {
        aux.apply(hdr);
        aux.apply(hdr);
    }
}

[smolkaj]

Good enough to get switch.p4_16 to compile & run :) 👍
Time to run some tests!